a large sum of+不可数名词
adj.巨款(数目可观的)
adj.He must have earned a large sum of money.
adj.他一定是挣了一笔巨款.
例如
The idea that gossips like to collect _____ peculiar informatio rarely surprises us.
A.a large sum of
B.a large quantity of
a large sum of是指一大笔钱或现金,而不是指一大笔信息.a large sum of也同样修饰不可数的money；
a large quantity of是大量的意思,修饰不可数名词.
这个句子的意思是：
那个多嘴婆热心于收罗一大堆稀奇古怪的信息很少能让我们感到惊讶的.